/*******************************************************************************
 * Copyright (c) 2012 itemis AG (http://www.itemis.eu) and others.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Author - Sebastian Zarnekow
 * See https://github.com/szarnekow/xtend-euler 
 *******************************************************************************/
 package euler

import java.util.List

/**
 * In the 20×20 grid below, four numbers along a diagonal line have been marked in red.
 *
 * 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
 * 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
 * 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
 * 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
 * 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
 * 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
 * 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
 * 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
 * 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
 * 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
 * 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
 * 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
 * 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
 * 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
 * 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
 * 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
 * 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
 * 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
 * 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
 * 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
 *
 * The product of these numbers is 26 × 63 × 78 × 14 = 1788696.
 *
 * What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20×20 grid?
 *
 * @see http://projecteuler.net/problem=11
 */
class Solution_011 {

	def static void main(String[] args) {
		new Solution_011().solve
	}

	def void solve() {
		val gridAsString = '''
			08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
			49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
			81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
			52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
			22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
			24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
			32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
			67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
			24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
			21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
			78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
			16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
			86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
			19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
			04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
			88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
			04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
			20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
			20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
			01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
		'''.toString
		var rows = 20
		var columns = 20
		val it = gridAsString.split("\\r?\\n").map[ split(' ').map[ s | Integer.valueOf(s) ].toList ].toList
		var result = 0
		for(c: 0..columns-4) {
			for(r: 0..rows-1) {
				result = result.max($(c, r), $(c + 1, r), $(c + 2, r), $(c + 3, r))
			}
			for(r: 0..rows-4) {
				result = result.max($(c, r), $(c + 1, r + 1), $(c + 2, r + 1), $(c + 3, r + 3))
			}
			for(r: 4..rows-1) {
				result = result.max($(c, r), $(c + 1, r - 1), $(c + 2, r - 1), $(c + 3, r - 3))
			}
		}
		for(c: 0..columns-1) {
			for(r: 0..rows - 4) {
				result = result.max($(c, r), $(c, r + 1), $(c, r + 2), $(c, r + 3))
			}
		}
		for(c: 4..columns-1) {
			for(r: 0..rows - 4) {
				result = result.max($(c, r), $(c - 1, r + 1), $(c - 2, r + 2), $(c - 3, r + 3))
			}
		}
		println(result)
	}

	def $(List<List<Integer>> lists, int column, int row) {
		lists.get(column).get(row)
	}

	def max(int current, int a, int b, int c, int d) {
		Math.max(current, a * b * c * d)
	}

}